In some cases, IP packets are transmitted from a plurality of transmission apparatuses to one reception apparatus through an internet protocol (IP) network in different time periods. A format of IP packets used for communication is well known (see, for example, Non Patent Literatures 1 to 3).
There is a need to unfailingly set basic connection information in an IP packet every time IP communication is performed. In particular, setting of a transmission source IP address, a destination IP address, a transmission source port number and a transmission destination port number in a header of an IP packet is indispensable. These information items: a transmission source IP address, a destination IP address, a transmission source port number and a transmission destination port number are referred to as network parameters in this specification. A conventional reception apparatus selects IP packets to be stored in a buffer by checking network parameters in received IP packets.
A system in which streams of video to be relayed from three sites A, B, and C are transmitted to a site Z through an IP network will be considered. More specifically, video transmission from the site A to the site Z is performed from 10:00 to 12:00; video transmission from the site B to the site Z is performed from 12:30 to 14:30; and video transmission from the site C to site the Z is performed from 15:00 to 17:00. transmission apparatuses that transmit IP packets for the streams of videos are installed at the sites A, B, and C, and a reception apparatus hat receives IP packets transmitted from these sites is installed at the site Z.
There is, therefore, a need to perform a network parameter setting change operation on the reception apparatus at site Z in each of a time period from 9:30 to 10:00 for the site A, a time period from 12:00 to 12:30 for the site B and a time period from 14:30 to 15:00 for the site C before relays from the sites A to C.